Impeller for centrifugal pumps



Nov. 5, 1940. FQB, ALLEN 2,220,669

IMPELLER FOR CENTR IFUGAL PUMPS Original Filed June 26, 1956 INVENTOR. PEA/VA .B ALLEN ATTORNEYS atented Nov,

UNIT-EPA mum- OF FlCE 2,220,669 I a IMPEILEB Fort CENTBIEUGAL PUMPS 20mm. x01. 103-115) This invention relates to pumps and more particularly to pumps of the type which are adapted to handle abrasivemixtures, acids orotherymaf terials which may have a harmful effect on the pumpparts. V l p The present application constitutes a division of my co-pending United'statespatent application Serial No. 87,567, filed June 26, 1936 In describingrmyinvention reference will be made particularly to thetype of pump which is designed primarily-tohandle mixtures of sand or gravel and water. It will beun'derstood, however, that pumps embodying my improvements.

may be adapted to handle acid or othersolution's which attack the usual metal pump.

It has been proposedflto line centrifugal pumps I with rubber to reduce the wear on the pum'nparts caused by the abrasive action of the materials; being pumped. It has also been proposedto'flush' the clearance spaces between the impeller and; housing of a centrifugal pump with clea'r'water to prevent the entry of abrasive material into.

these clearance spaces and thus increase the life of the pump and maintain its efliciency.

It is an object of the present invention to provide an improved rubber linedcentrifugal pump 1 having an improved"type of rubber covered impeller; theprovisionofan improved rubber "covered pump impeller structure and. method] or; r making same; and the provision of a centrifugal pump for handling abrasive or other liquids which may be harmful to metal parts which will have a long trouble-free life and be economical'toman'ufacture.

The above and other objects of my invention will appear from the following description of one embodiment thereof, reference being had to the accompanying drawing in which:

Fig. 1 is a sideelevation'of a centrifugalpump 4o embodying my improvements, the top ghalf of the pump being illustrated in vertical cross section; V Fig. 2 is an end view of the pump impeller taken;

from the suction side of the pump, the lower half ofthe figure showing the uncovered impeller frame, and the upper half showing the'rubber cover vulcanized on. Parts of the impeller are broken away for clearer illustration;

Fig, 3 is a fragmentary cross section through the impeller frame shown in Fig. 2; Fig. 4 is an enlargedcl'oss sectional view of the shaft end of the impeller. 1 My improved pump (referring particularly to Figure 1) comprises a housing indicated generally at A and an impeller indicated generally at B. The impeller is mounted on a shaft I which ex- 1 cover maybe securely attached. In making the impeller the frame is preferably placed in a suiting in the desired form.

tends, out through a suitable packing 2, in the housing. A and has threaded engagement at its inner end with theihub of the impeller B. As seen in'Figures land-1 the impeller shaft I ls formed with a shoulder l 'and is grooved at the 5 base of the threads which engage the impeller as seen at l A metal disc or washer i 'is disposed between the end of the shaft 1 and the impeller hub and is clamped between. the impeller'hub and. the shoulder l of the shaft. Apin or pins I are 10 supported in the impeller'hub and extend through r the rubber covering Ii of the impeller and through thewasher l., The washer I? serves to hold the rubber impeller cover in position at the hub and the pins, i prevent rotation. ofthe 15 washer. IF relative to the rubber impeller cover I l whenthe shaft i ls screwed into the impeller, hub. A rubber washer 1 lies in the groove l and is effective in preventing the entry of water or foreign material into the threads ,of; the shaft I.

" Qnithe opposite sideof the housing A is the inletopening 3 wh t is preferably provided with atubular rubber liner 4 having a flanged portion 7 ages the suction side cover platei of A includes the volute 8 which is lined bygl'the rubber linerfLqThe liner 1 has a tubular portion which extends up through the pump outlet. A generally discshaped rubber liner member 9 covers the shaft side of the housing A and the rub- 3o ber liner member C covers the tion side plate 5. Thus, the entire inside 0ft epump housing islinedwith rubberv by the tubul rubber sleeve 4 and the liners c; 1 and a. I e

The impeller B comprisesa metallic skeleton or 5" frame (illustrated in detailin Figures 2 and 3) which is molded into the soft, resilient, stretch able rubber sheath I l., Th impeller frame ineludes a perforated shaft sideshroud platelll, transversely extending perforated bladesupport- 0 mg portions 10' and a perforated inlet side shroud I plate in". .The blade members ill and the plates in and ill" are. perforated so that the rubber ably formed mold and surrounded by raw rubber of suitable composition. When the rubber is Vill canized under pressure a firm bond is secured between the skeleton and the covering and the holes and spaces in the skeleton are filled with rubber', the danger of the rubber cover; coming loose is completely eliminated. The metal frame forms a rigid support for the impellersldes and bladesand holds the relatively softrffibb'er cover- A. .The'center section of thethousing 25' Referring particularly to Figures 1, 2 and 3 it will be noted that the shroud plates l and I0" and the blade portions II) are perforated. In the embodiment illustrated the perforations in the shroud plate take the form of elongated arcuate slots which slots are spacedrelatively close together in a'r'adial direction. In the blade members the perforations take the form of holes arranged in rows in the blade supporting portions of the frame.

These perforations have a special function in my improved rubber covered pump impeller. I have found that when soft rubber, or like resilient material of the type preferably employed in lining my pumps, is placed under tension and is then subjected to the abrasive action of sand, gravel or other abrasives, it wears away much more rapidly than is the case when the rubber covering or lining is inert or in unstretched condition. I believe that the relatively rapid wear which occurs when the rubber is stretched is due to the fact that when under tension any.

miute abrasions whichmay occur on the surface of the rubber are immediately stretched and held open and consequently enlarged by the impact of succeeding abrasive particles. However, when the rubber is inert the impact of aparticle against the surface ofthe rubber does not tend to break the surface and cause resulting wear as readily as when the ruber is under stress. Also, even if a break occurs, it is not held open to cause! a rough spot which willbe subject to relatively rapid additional wear. Therefore, by providing an impeller frame to which the rubber covering is integrally molded 'and providing a relatively close spacing, particularly in a radial direction, of the perforations thr'ough'which the rubber cover extends, I have produced arubber covered impeller in which, under all operating conditions, the surface of the rubber will be substantially inert or unstretched. This overcomes the difiiculties experienced with other types of rubber covered impellers in which the rubber covering may be molded to a frame but in which the rubber covering is not attached or locked to the frame at closely spaced radial intervals. t I

It will be understood that when' the impeller is rotating, centrifugal force tends to act radially on the rubber covering and stretch the covering between points of positive attachment to the metal backing. By placing the points of attachment to the backing so close together that substantial stretch of the rubber cover therebetween, due to centrifugal force, is positively prevented I have produced an impeller having a maximum life and resistance to abrasive wear. This feature of my invention has proved very successful in actual use and I have found that my rubber surfaced impellers, in 'which the rubber surface is positively held against stretch due to forces imposed thereon during operation, wear much'longer, under the same operating conditions, than other types of rubber covered impellers.

Although I have illustrated and described only 7 liquids containing abrasive solids, comprising a one-piece metal skeleton and a rubber covering therefor, said skeleton consisting of a shroud plate, a shroud ring and a plurality of arc shaped blades therebetween, said shroud disc having a central portion provided with a forwardly projecting dome and a rearwardly projecting, threaded, shaft receiving hub and having in the portion outside of said central portion circumferentially extending openings arranged in a plurality of concentric rows, said shroud ring having a central inlet passageand circumferentially extending openings arranged in a'plurality of concentric rows, each of said blades having a length as measured radially of said skeleton which is less than the radial width of the shroud ring and having a plurality of openings arranged in rows extending lengthwise thereof, said cov-. ering consistingof a single piece of soft, resilient and stretchable rubber which covers the disc, v ring and blades of the skeleton and fills the said openings therein, said openings being so numerous and. so disposed in the plate, ring and blades that they maintain the surface of thecovering in substantially unstretchable condition when. the impeller isin use, the blade coverings extending inwardly to the inner edge of said shroud ring and then curving sharply and decreasing in circumferential width and axial height until they merge with the covering'of the dome of the shroud also. j

2. An impeller for a centrifugal pump for liquid containing abrasive solids, comprising a one-piece metal skeleton anda rubber covering therefor, said skeleton consisting of a shroud plate, a shroud ring and a plurality of are shaped blades therebetween, said shroud disc having an, imperforate central portion and an outer portion, said shroud ring having a central opening, both the ring and the outer portion of the disc having a plurality of concentric rows of circumferentially extending openings, each of said blades having a plurality of openings arranged in rows extending lengthwise thereof, said covering consisting of a single piece of soft, resilient and stretchable rubber which covers the disc,

' ring and blades of the skeleton and fills the said openings therein, said openings being so numerv ous and so disposed in the plate, ring andblades that they maintain the surface of the covering in substantially unstretched condition when the impeller is in use.

FRANK B. ALLEN. 

